[DanPatrick10]

Aside from needing a tune-up, my 300zx backfires after shifting at low speeds. It does not backfire while driving on the highway.

[TxGreaseMonkey]

Selected Possibilities:

. Check for vacuum leaks at intake manifold or vacuum hoses.
. Check idle rpm with a tach.
. Check timing with a timing light.
. Ensure spark plugs are in good shape.
. Perform compression test on engine.
. Check EGR system.
. Check for damaged valve springs or sticking valves.
. Check oxygen sensor.